Horsepen Dam Reservoir Report

Last Updated: December 5, 2025

Horsepen Dam, located in Loudoun, Virginia, is a key asset for water supply purposes in the region.


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Summary

This earth-type dam stands at a height of 50 feet and spans a length of 600 feet, with a storage capacity of 15,200 acre-feet. The dam sits on Horsepen Run and is under the regulatory oversight of the Department of Conservation and Recreation in Virginia.

With a high hazard potential, Horsepen Dam is regularly inspected to ensure its structural integrity and overall condition. The most recent assessment in July 2021 deemed the dam to be in satisfactory condition. In the event of an emergency, the dam's emergency action plan (EAP) is essential for preparedness and response, although its last revision dates back to 2015. Horsepen Dam plays a crucial role in managing water resources in the area and highlights the importance of maintaining and monitoring infrastructure to mitigate potential risks associated with climate variability and water resource management.

Dam Length

600

Dam Height

50

River Or Stream

Horsepen Run

Primary Dam Type

Earth

Surface Area

18

Hydraulic Height

50

Drainage Area

22.8

Nid Storage

15200

Structural Height

50

Hazard Potential

High

Nid Height

50
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.